Fix integer overflow in BitstreamReader::ReadBit() called from H265SpsParser::ParseSpsInternal(). <rdar://117763685>
Pull request: https://github.com/WebKit/WebKit/pull/19815
Committed 270062@main (b05fd50ce4ab): <https://commits.webkit.org/270062@main> Reviewed commits have been landed. Closing PR #19815 and removing active labels.